Prevalence of Trachoma in Northern Benin: Results from 11 Population-Based Prevalence Surveys Covering 26 Districts.

AIMS: We sought to evaluate trachoma prevalence in all suspected-endemic areas of Benin. METHODS: We conducted population-based surveys covering 26 districts grouped into 11 evaluation units (EUs), using a two-stage, systematic and random, cluster sampling design powered at EU level. In each EU, 23 villages were systematically selected with population proportional to size; 30 households were selected from each village using compact segment sampling. In selected households, we examined all consenting residents aged one year or above for trichiasis, trachomatous inflammation - follicular (TF), and trachomatous inflammation - intense. We calculated the EU-level backlog of trichiasis and delineated the ophthalmic workforce in each EU using local interviews and telephone surveys. RESULTS: At EU-level, the TF prevalence in 1-9-year-olds ranged from 1.9 to 24.0%, with four EUs (incorporating eight districts) demonstrating prevalences ≥5%. The prevalence of trichiasis in adults aged 15+ years ranged from 0.1 to 1.9%. In nine EUs (incorporating 19 districts), the trichiasis prevalence in adults was ≥0.2%. An estimated 11,457 people have trichiasis in an area served by eight ophthalmic clinical officers. CONCLUSION: In northern Benin, over 8000 people need surgery or other interventions for trichiasis to reach the trichiasis elimination threshold prevalence in each EU, and just over one million people need a combination of antibiotics, facial cleanliness and environmental improvement for the purposes of trachoma's elimination as a public health problem. The current distribution of ophthalmic clinical officers does not match surgical needs

Sanitation and water supply coverage thresholds associated with active trachoma: Modeling cross-sectional data from 13 countries.

BACKGROUND: Facial cleanliness and sanitation are postulated to reduce trachoma transmission, but there are no previous data on community-level herd protection thresholds. We characterize associations between active trachoma, access to improved sanitation facilities, and access to improved water sources for the purpose of face washing, with the aim of estimating community-level or herd protection thresholds. METHODS AND FINDINGS: We used cluster-sampled Global Trachoma Mapping Project data on 884,850 children aged 1-9 years from 354,990 households in 13 countries. We employed multivariable mixed-effects modified Poisson regression models to assess the relationships between water and sanitation coverage and trachomatous inflammation-follicular (TF). We observed lower TF prevalence among those with household-level access to improved sanitation (prevalence ratio, PR = 0.87; 95%CI: 0.83-0.91), and household-level access to an improved washing water source in the residence/yard (PR = 0.81; 95%CI: 0.75-0.88). Controlling for household-level water and latrine access, we found evidence of community-level protection against TF for children living in communities with high sanitation coverage (PR80-90% = 0.87; 95%CI: 0.73-1.02; PR90-100% = 0.76; 95%CI: 0.67-0.85). Community sanitation coverage levels greater than 80% were associated with herd protection against TF (PR = 0.77; 95%CI: 0.62-0.97)-that is, lower TF in individuals whose households lacked individual sanitation but who lived in communities with high sanitation coverage. For community-level water coverage, there was no apparent threshold, although we observed lower TF among several of the higher deciles of community-level water coverage. CONCLUSIONS: Our study provides insights into the community water and sanitation coverage levels that might be required to best control trachoma. Our results suggest access to adequate water and sanitation can be important components in working towards the 2020 target of eliminating trachoma as a public health problem

Risk factors associated with failing pre-transmission assessment surveys (pre-TAS) in lymphatic filariasis elimination programs: Results of a multi-country analysis.

Achieving elimination of lymphatic filariasis (LF) as a public health problem requires a minimum of five effective rounds of mass drug administration (MDA) and demonstrating low prevalence in subsequent assessments. The first assessments recommended by the World Health Organization (WHO) are sentinel and spot-check sites-referred to as pre-transmission assessment surveys (pre-TAS)-in each implementation unit after MDA. If pre-TAS shows that prevalence in each site has been lowered to less than 1% microfilaremia or less than 2% antigenemia, the implementation unit conducts a TAS to determine whether MDA can be stopped. Failure to pass pre-TAS means that further rounds of MDA are required. This study aims to understand factors influencing pre-TAS results using existing programmatic data from 554 implementation units, of which 74 (13%) failed, in 13 countries. Secondary data analysis was completed using existing data from Bangladesh, Benin, Burkina Faso, Cameroon, Ghana, Haiti, Indonesia, Mali, Nepal, Niger, Sierra Leone, Tanzania, and Uganda. Additional covariate data were obtained from spatial raster data sets. Bivariate analysis and multilinear regression were performed to establish potential relationships between variables and the pre-TAS result. Higher baseline prevalence and lower elevation were significant in the regression model. Variables statistically significantly associated with failure (p-value ≤0.05) in the bivariate analyses included baseline prevalence at or above 5% or 10%, use of Filariasis Test Strips (FTS), primary vector of Culex, treatment with diethylcarbamazine-albendazole, higher elevation, higher population density, higher enhanced vegetation index (EVI), higher annual rainfall, and 6 or more rounds of MDA. This paper reports for the first time factors associated with pre-TAS results from a multi-country analysis. This information can help countries more effectively forecast program activities, such as the potential need for more rounds of MDA, and prioritize resources to ensure adequate coverage of all persons in areas at highest risk of failing pre-TAS

Exploring water, sanitation, and hygiene coverage targets for reaching and sustaining trachoma elimination: G-computation analysis.

BACKGROUND: Trachoma is the leading infectious cause of blindness. To reduce transmission, water, sanitation, and hygiene (WaSH) improvements are promoted through a comprehensive public health strategy. Evidence supporting the role of WaSH in trachoma elimination is mixed and it remains unknown what WaSH coverages are needed to effectively reduce transmission. METHODS/FINDINGS: We used g-computation to estimate the impact on the prevalence of trachomatous inflammation-follicular among children aged 1-9 years (TF1-9) when hypothetical WaSH interventions raised the minimum coverages from 5% to 100% for "nearby" face-washing water (<30 minutes roundtrip collection time) and adult latrine use in an evaluation unit (EU). For each scenario, we estimated the generalized prevalence difference as the TF1-9 prevalence under the intervention scenarios minus the observed prevalence. Data from 574 cross-sectional surveys conducted in 16 African and Eastern Mediterranean countries were included. Surveys were conducted from 2015-2019 with support from the Global Trachoma Mapping Project and Tropical Data. When modeling interventions among EUs that had not yet met the TF1-9 elimination target, increasing nearby face-washing water and latrine use coverages above 30% was generally associated with consistent decreases in TF1-9. For nearby face-washing water, we estimated a ≥25% decrease in TF1-9 at 65% coverage, with a plateau upon reaching 85% coverage. For latrine use, the estimated decrease in TF1-9 accelerated from 80% coverage upward, with a ≥25% decrease in TF1-9 by 85% coverage. Among EUs that had previously met the elimination target, results were inconclusive. CONCLUSIONS: Our results support Sustainable Development Goal 6 and provide insight into potential WaSH-related coverage targets for trachoma elimination. Targets can be tested in future trials to improve evidence-based WaSH guidance for trachoma

Tropical Data: Approach and Methodology as Applied to Trachoma Prevalence Surveys

PURPOSE: Population-based prevalence surveys are essential for decision-making on interventions to achieve trachoma elimination as a public health problem. This paper outlines the methodologies of Tropical Data, which supports work to undertake those surveys. METHODS: Tropical Data is a consortium of partners that supports health ministries worldwide to conduct globally standardised prevalence surveys that conform to World Health Organization recommendations. Founding principles are health ministry ownership, partnership and collaboration, and quality assurance and quality control at every step of the survey process. Support covers survey planning, survey design, training, electronic data collection and fieldwork, and data management, analysis and dissemination. Methods are adapted to meet local context and needs. Customisations, operational research and integration of other diseases into routine trachoma surveys have also been supported. RESULTS: Between 29th February 2016 and 24th April 2023, 3373 trachoma surveys across 50 countries have been supported, resulting in 10,818,502 people being examined for trachoma. CONCLUSION: This health ministry-led, standardised approach, with support from the start to the end of the survey process, has helped all trachoma elimination stakeholders to know where interventions are needed, where interventions can be stopped, and when elimination as a public health problem has been achieved. Flexibility to meet specific country contexts, adaptation to changes in global guidance and adjustments in response to user feedback have facilitated innovation in evidence-based methodologies, and supported health ministries to strive for global disease control targets

Épidémiologie de la bilharziose urinaire et des géohelminthiases chez les jeunes scolaires des zones lacustres de la commune de So-Ava, sud-Bénin

International audienceObjective: In the tropics, infections by Schistosoma haematobium and soil-transmitted helminths speciesare widespread and Republic of Benin is no exception. This study aims to assess the epidemiologicalstatus of urogenital schistosomiasis and soil-transmitted helminths in schoolchildren of Sô-Ava town in theDepartment of Atlantic in Southern Benin.Methodology and Results: The biological material was composed of urine and stool collected from fromPublic Primary Schools in Sôchanhoué, Sôtchanhoué Quarter and Sô-Zounko between April to August2012 . Six hundred and four urine samples were examined by filtration technique and 363 stool sampleswere examined by Kato-Katz test. Malacological surveys were conducted to assess the diversity offreshwater snails and determine the snail species involved in the transmission of schistosomiasis. Theresults showed infection rates of S. haematobium of 22.22% (N = 153), 21.43% (N = 182) and 46.47% (N =269) in the three prospected sites, respectively, with an overall infection rate of 32.78% (N = 604) with asmany boys as girls infected and children 7 to 8 years of age the most affected. Three species of soiltransmittedhelminths were found with an overall prevalence of 12.12% (N = 44) of people infected with atleast one of the three parasites Ascaris lumbricoides, Trichuris trichiura or Enterobius vermicularis. Theresults showed that the parasite densities of S. haematobium and soil-transmitted helminths were thegreatest in children aged 7 to 8 years, especially boys. Three species of freshwater snails known asintermediate hosts for schistosomes were collected: Bulinus forskalii, B. globosus and B. truncatus.Conclusion: This study was used to assess the level of endemicity of urinary schistosomiasis and soiltransmittedhelminths in human populations of the Nokoue Lake area and allows considering theappropriate means of controlling these parasites.Objectif : Dans les zones intertropicales, les infestations par Schistosoma haematobium et autres espècesd’helminthes sont très répandues et le Bénin ne fait pas exception. Cette étude a pour objectif d’évaluer lestatut épidémiologique de la Bilharziose urogénitale et des géohelminthiases chez les enfants d’âgescolaire de la commune de Sô-Ava, Département de l’Atlantique dans le Sud-Bénin.Méthodologie et Résultats : Le matériel biologique est composé d'urines et de selles provenant de jeunesécoliers âgés de 4 à 8 ans et scolarisés dans les Ecoles Primaires Publiques de Sô-Tchanhoué village, Sô-Tchanhoué Quartier et de Sô-Zounko de la commune de Sô-Ava. Les trois sites de prospection font partiede la commune de Sô-Ava. Six cent quatre échantillons d'urine ont été examinés par la technique defiltration et 363 échantillons de selles examinées par la technique de Kato-Katz. Les résultats d'analyse desurines révèlent les prévalences respectives à S. haematobium de 22,22% (N=153) ; 21,43% (N=182) et46,47% (N=269) dans les trois villages pour une prévalence globale de 32,78% (N= 604) avec autant degarçons que de filles infestés et les enfants de 7 à 8 ans constituent la tranche d’âge la plus touchée. Lesrésultats d'analyse des selles révèlent trois espèces d'helminthes avec une prévalence globale de 12,12%(N=44) de personnes infestées par au moins un des trois parasites Ascaris lumbricoides, Trichuris trichiuraet Enterobius vermicularis. Aucun oeuf de S. mansoni n’a été observé dans les selles. Les résultatsmontrent enfin que les charges parasitaires de S. haematobium et des géohelminthes étaient plusimportantes chez les enfants de 7 à 8 ans, en particulier chez les garçons. Les prospections malacologiques ont été réalisées afin d’évaluer la diversité malacologique et déterminer les mollusquesimpliqués dans la transmission des schistosomes. Trois espèces de mollusques connues comme hôtesintermédiaires de schistosomes ont été collectées Bulinus forskalii, B. globosus et B. truncatus.Conclusion : Cette étude a permis d’évaluer le niveau d’endémicité de la bilharziose urogénitale et desgéohelminthes au niveau des populations humaines de cette zone lacustre et permet d’envisager lesmoyens adéquats pour le contrôle de ces parasitose

Pilot Assessment of Soil-Transmitted Helminthiasis in the Context of Transmission Assessment Surveys for Lymphatic Filariasis in Benin and Tonga

<div><p>Background</p><p>Mass drug administration (MDA) for lymphatic filariasis (LF) programs has delivered more than 2 billion treatments of albendazole, in combination with either ivermectin or diethylcarbamazine, to communities co-endemic for soil-transmitted helminthiasis (STH), reducing the prevalence of both diseases. A transmission assessment survey (TAS) is recommended to determine if MDA for LF can be stopped within an evaluation unit (EU) after at least five rounds of annual treatment. The TAS also provides an opportunity to simultaneously assess the impact of these MDAs on STH and to determine the frequency of school-based MDA for STH after community-wide MDA is no longer needed for LF.</p><p>Methodology/Principal Findings</p><p>Pilot studies conducted in Benin and Tonga assessed the feasibility of a coordinated approach. Of the schools (clusters) selected for a TAS in each EU, a subset of 5 schools per STH ecological zone was randomly selected, according to World Health Organization (WHO) guidelines, for the coordinated survey. In Benin, 519 children were sampled in 5 schools and 22 (4.2%) had STH infection (<i>A. lumbricoides</i>, <i>T. trichiura</i>, or hookworm) detected using the Kato-Katz method. All infections were classified as light intensity under WHO criteria. In Tonga, 10 schools were chosen for the coordinated TAS and STH survey covering two ecological zones; 32 of 232 (13.8%) children were infected in Tongatapu and 82 of 320 (25.6%) in Vava'u and Ha'apai. All infections were light-intensity with the exception of one with moderate-intensity <i>T. trichiura</i>.</p><p>Conclusions</p><p>Synchronous assessment of STH with TAS is feasible and provides a well-timed evaluation of infection prevalence to guide ongoing treatment decisions at a time when MDA for LF may be stopped. The coordinated field experiences in both countries also suggest potential time and cost savings. Refinement of a coordinated TAS and STH sampling methodology should be pursued, along with further validation of alternative quantitative diagnostic tests for STH that can be used with preserved stool specimens.</p></div

Sampling strategy for coordinated TAS and STH surveys.

1<p>5 schools per ecological zone; all schools randomly selected from TAS sample except two schools in Tonga that were included in 2001–2002 STH survey.</p

Schistosomiasis and Soil Transmitted Helminths Distribution in Benin: A Baseline Prevalence Survey in 30 Districts

<div><p>In 2013, Benin developed strategies to control neglected tropical diseases and one of the first step was the disease mapping of the entire country in order to identify endemic districts of schistosomiasis and soil transmitted helminths (STH). This study was carried out in 30 of the 77 districts of Benin. Of these 30 districts 22 were previously treated for Lymphatic Filariasis (LF) using the Ivermectin and Albendazole combination. In each district, five schools were selected and 50 children aged 8 to 14 years were sampled in each school, making a total of 250 children sampled in the district. The schools were selected mainly according to their proximity to lakes or any bodies of water that were likely to have been used by the children. Samples of faeces and urine were collected from each pupil. Urinary schistosomiasis was identified using the urine filtration technique while STH and intestinal schistosomiasis were identified through the Kato Katz method. Overall a total of 7500 pupils were surveyed across 150 schools with a gender ratio of 1:1. Hookworm was identified in all 30 districts with a prevalence ranging from 1.2% (95%CI: 0.0–2.5) to 60% (95%CI: 53.9–66.1). <i>Ascaris lumbricoides</i> was detected in 19 districts with a prevalence rate between 1% (95%CI: 0.0–2.2) and 39% (95%CI: 32.9–45.0). In addition to these common STH, <i>Trichuris trichiura</i>, <i>Enterobius vermicularis</i> and <i>Strongyloides stercoralis</i> were found at low prevalence. Only 16 districts were endemic to <i>Schistosoma mansoni</i>, while 29 districts were endemic to <i>S</i>. <i>haematobium</i>. The <i>S</i>. <i>haematobium</i> prevalence ranged from 0.8% (95% CI: 0.0–1.9) to 56% (95% CI: 50.2–62.5) while the prevalence of <i>S</i>. <i>mansoni</i> varied from 0.4% (95%CI: 0.0–1.2) to 46% (95% CI: 39.8–52.2). The 22 districts, where LF was successfully eliminated, still require mass drug administration (MDA) of albendazole indicating that school-based MDA would be needed even after LF elimination in districts co-endemic to LF and STH in Benin.</p></div